The present invention relates to a container and a loader for an article such as a substrate necessary to be kept under the condition of high cleanliness during transportation and working, in particular the present invention relates to transporting means (hereinafter referred to as “loader”) to transport the substrate or the like between the container used for transporting the substrate or the like between a low cleanliness room and a high cleanliness room for working the substrate or the like.
The present invention is applicable to any article necessary to be kept under the condition of high cleanliness during transportation and working. It is described hereunder in relation to a semiconductor substrate such as a silicon wafer or a liquid crystal substrate, in particular a semiconductor wafer as an example, however, the present invention is not limited to the above.
The semiconductor substrate, in particular semiconductor wafer is contaminated when dust or vaporized organic compounds (hereinafter referred to as “dust”) are attached thereto, thus leading to a lower productivity, i.e., the rate of producing a high-quality of product is low. It is therefore necessary to maintain high cleanliness in the surroundings of the substrate or the like when the semiconductor wafer is transported or worked. More specifically, the semiconductor wafer is one of the articles necessary to be kept under the condition of high cleanliness during transportation and working (hereinafter referred to as “dust free article”).
In general, the semiconductor wafer is worked in a room where cleanliness is high (hereinafter referred to as a “high cleanliness room”), i.e., so called a clean room. On the other hand, when the semiconductor wafer is transported, the semiconductor wafer is received in an air-tight sealed container (hereinafter referred to as a “container”), the inside of which is kept under the condition of high cleanliness, and then, the container with the semiconductor wafer received therein is transported. Thus, the semiconductor wafer can be transported through a room in which the degree of cleanliness is low or outdoor (hereinafter referred to as “low cleanliness room”), avoiding the semiconductor wafer from being contaminated during transportation.
There is disposed a loader with an opening portion, which can be closed, in the border portion between the high cleanliness room and the low cleanliness room. The semiconductor wafer is transported by the above loader from the inner space of the container with high cleanliness for working the semiconductor wafer to the high cleanliness room (hereinafter referred to as “loading”), in addition, from the high cleanliness room to the inner space of the container with high cleanliness for transferring to another treatment step (hereinafter referred to as “unloading”). More specifically, the semiconductor wafer is moved through the above opening portion. The container has a cover (i.e., lid) in a direction to the opening portion of the loader, which cover is opened when the semiconductor wafer is transferred.
When the semiconductor wafer is not transported, the opening portion of the loader is kept closed so as to prevent dust from floating into the high cleanliness room from the low cleanliness room. A door may be disposed in the opening portion so that the opening portion can be opened or closed by the door.
In this case, the door may be large enough to completely close the opening portion. In addition, the door may be of the size in which the door is about 5 mm smaller in each side than respective side of the opening portion in such manner that there is provided an aperture (open space) or a gap between the door and the opening portion, while the air pressure in the high cleanliness room is kept higher than that in the lower cleanliness room, thus air flows through the aperture from the high cleanliness room to the low cleanliness room.
The following standards for the above container and loader are proposed and applied: SEMI (Semiconductor Equipment and Material International) Standard E47.1 [Box/Pod (FOUP)], E15.1 [Tool Load Port], E57 [Kinematic Coupling], E62 [Front-Opening Interface Standard (FIMS)], E63 [Box/Opener to Tool Standard (BOLTS)] and the like (hereinafter referred to as “Standard”).
The semiconductor wafer is transported through the opening portion between the container with the door opened and the high cleanliness room. However, as described above, it is essential to consider that the semiconductor wafer should not be contaminated by dust. It is therefore necessary to note that the dust floating in the low cleanliness room, the dust attached to the container, particularly, the cover of the container, the dust attached to the door of the loader in the side of the lower cleanliness room, or the dust generated along with the driving of the loader has to be prevented from floating into the high cleanliness room.
As one of the methods to realize the above requirement to prevent the dust from floating into the high cleanliness room, there is disclosed the method in German Patent Application No. 19511024-2 (filed on Mar. 28, 1995), German Patent Application No. 19542646-2 (filed on Nov. 15, 1995), and Japanese Patent Laid-Open Publication No. 8-279546. The method is described hereunder with reference to FIG. 1.
A wall 105 separates a high cleanliness room in the right hand side in the drawing from a low cleanliness room in the left hand side in the drawing. An opening portion of the wall 105 is closed by the door 104 of a loader. A semiconductor wafer 101 is received inside of a container 102, and dust is prevented from floating into the container by a cover 103. The semiconductor wafer is transferred from the inside of the container to the high cleanliness room in the drawing as follows: the container 102 is mounted on a stage 107 of the loader; the cover 103 of the container 102 is fixed onto the door 104 of the loader so as to be unified; thus fix-unified cover 103 and door 104 are pulled out in a horizontal direction by a driving apparatus disposed in the high cleanliness room, and then lowered vertically to be moved eventually to the position illustrated with a dotted line in the drawing; the container 102 and the opening portion of the wall 105 are fully opened; the semiconductor wafer 101 is transferred to the high cleanliness room; and the semiconductor wafer 101 is worked in the high cleanliness room.
In the above process, however, since the cover 103 and the door 104 of the loader are moved into the high cleanliness room, the dust attached thereto is also moved and scattered into the high cleanliness room. Although it is described in the above disclosure that the dust is fixed within a portion tightly held between the cover 103 and the door 104 so that the dust is not scattered in the high cleanliness room, it is however difficult to completely fix the dust so as not to be scattered. It is therefore difficult to prevent the dust from being scattered.
In addition, since the driving apparatus 106 for moving the cover 13 and the door 104 to the high cleanliness room is required to be disposed in the high cleanliness room, the driving apparatus 106 generates dust in the high cleanliness room. When movable portions in the driving apparatus, such as a motor or a cylinder, are operated, dust is generated by friction of the portions. Furthermore, lubricants applied to the movable portions are evaporated in the high cleanliness room, thus it is impossible to keep high cleanliness therein.
Furthermore, since the cover 103 and the door 104 are moved in a horizontal direction by the driving apparatus 106, and then lowered in a vertical direction, the driving apparatus 106 is required to drive the cover and the door in two directions, thus the apparatus becomes in such complex construction that the accuracy of the operation of the apparatus is apt to be lowered and at the same time the cost of the apparatus increases. Furthermore, the time required for one cycle of the operation increases to lead the production efficiency to be poor.
Furthermore, the dust is inevitably generated when the driving apparatus is kept operable, controlled and repaired. Since the driving apparatus is disposed in the high cleanliness room, the dust is scattered in the high cleanliness room. In addition, when a worker carries out workings in the high cleanliness room, it is required to install equipment to remove the dust attached to the body of the worker, thus increasing the cost.
The present invention has been made to solve the above problems of the prior art. The object of the invention is therefore to provide a container and a loader for semiconductors by which a semiconductor wafer is received in a container and transported in a low cleanliness room, the semiconductor wafer is worked in a high cleanliness room, and the semiconductor wafer is transported between the container and high cleanliness room without causing dust to float into the high cleanliness room from the low cleanliness room, and generating dust in the high cleanliness room and with easy maintenance, control and repair of the apparatus.